[Study of a marker of free radical activity in myocardial infarction and in the prodromal syndrome].

Myocardial ischemia is accompanied by a release of free radicals (FR) derived from oxygen, elements having an important cytotoxic activity. These FR react with unsaturated lipids from the membrane fatty acids, leading possibly to a lysis of the membrane. This lipidic peroxidation of the fatty acids generates, in fact, endoperoxides, unstable lipid by-products and also with a cytotoxic activity. At the end of these reactions, cyclical compound and aldehydes are formed, and it is possible to titrate one of them, the malondialdehyde (MDA) which represents a marker of the aggression of the radicals on the membranes. We have therefore studied the appearance of MDA in the systemic venous blood and compared 10 patients with a threat syndrome (group I) to 8 other patients with acute myocardial infarction (group II). The plasma MDA level is measured upon admission (D1), on the 5th day (D2) and on the 12th day (D3) of the evolution. We have therefore found a significant elevation of MDA in the two groups of patients at D1 and D2, in comparison with the results obtained in a reference group of 15 normal patients (p less than 0.01). In the infarction group, the level of MDA on the 12th day (189 +/- 41 ng/ml) drops significantly as compared to the highest level noted upon admission and on the 5th day, called MDA peak (258 +/- 62 ng/ml, p less than 0.01). The MDA drop is less marked in group I of the threat syndromes.(ABSTRACT TRUNCATED AT 250 WORDS)